The need of human beings to build power plants in the energy production for the utilization of renewable energy sources consequently also produces direct damage to the nature itself, but additionally to the sources of livelihood, beneficial for the nature.
Migratory fish, especially Salmoniforms, the Anguilliformes, and/or alike, that migrate upstream back to their natal rivers to spawn encounter barriers in such rivers where the riverbed has been built with dams, such to be utilized in the industry of electricity production or in other power plants.
The passage over the power plant is blocked if no passing watercourse has been built. Even if there were such, the path of young migratory fish back downstream can be difficult, especially if the fish have to go through turbine tunnels. The fish may get hurt, and thus exposed to diseases. On the other hand, the passage by fish path passing the turbine tunnel wastes water, as does a fish ladder, out of which the latter is also quite expensive to build, but also leaves a mark on the landscape. Additionally, the fish may get damaged in the shallow pools when jumping from one to another, to yield a high risk of diseases.
On a further other hand, salmon fish, for example, are not attracted to going into deep waters, which in its part makes it difficult for young fish to return into the turbine tunnels or the passing by tunnels.
FIG. 1 discloses a fish ladder example in accordance with a known technique that facilitates access as such for the migratory fish 114 to swim upstream the flow, and thus cross the dam 116 which is crossing the watercourse 117A, 117B. As the FIG. 1 indicates, the fish ladder is quite heavily built, poorly if at all fitting to the landscape, but also expensive to construct, by casting the concrete, with the reinforcing and foundation works, including also the materials, the need of which is remarkable for such a large construction. The assembly of such also lasts long with all the land excavations that potentially mess up the landscape 115 and potentially also the waters downstream in the vicinity of the fish ladder.
In the example of the FIG. 1, the fish ladder 100 has been arranged by a structure to pass the watercourse 117A, 117B (the bending of the whole path of the watercourse would be even more expensive, if not the by-pass passage 100 done. Probably the energy obtainable from the flowing water 109 would not be utilizable, or just poorly if not at all during the constructions).
The water flowing in the riverbed of the terrain 115 (117A—downstream, 117B—upstream of the river bed) flows 109 partly via compartments with slots 101A, forming a channel 102 with a deepness 103 that are in communication together to the flow 109. The safety net 104 covers two such compartments, including under the net covered also the intermediate parts. The fish passage 100 has been arranged as gently ascending so that the elevation angle is 1:18-1:30, being gentler than the vertical climb of the dam 116 at the overflow 111 position, or at the middle of the dam 116 in the riverbed. Simultaneously, attraction water 107 from the upstream location of the riverbed 117B is flowing via the fish passage 100, so that the fish 114 find the entrance 106 of the fish passage 100 to swim upstream 117B the channel 102. The compartments with slots 101A are provided with small pass-through gates, wherein each compartment 101A can have a pool or a part thereof in which the fish 114 can rest between the rising steps, but the FIG. 1 also illustrates a compartment that is operative at the halfway as a resting pool 105 as a part of the fish ladder 100.
The disclosed example illustrates also that trash migration has been restricted by a diffuse net 110 at the downstream and by a trash sieve 112 upstream at the outlet 113 of the fish passage 102. Over flooding can be arranged as such by a spillover formation 108, 111 to some extent to produce attraction water 107 over the dam 116.
As an insert in FIG. 1 there is an illustration of the fish ladder structure at the left hand side corner, illustrating as an example of a compartment with slot 101A as a part of the fish ladder 100 to form a channel 102 structure of the passage 100. Depth 103 of a compartment and the slot 101A has been also illustrated in the FIG. 1. The gate formations 10p as a slot of the channel 102 are also illustrated by the insert.
The ladder according to known techniques can be also as composing of a straight watercourse being mounted into a biased elevating angle from a downstream location to an upstream location.
Thus the present designs of the solution of the water power plants cause that the fish reproduction, sports fishing activities and their derivatives, power plant electricity production and the aspects of the landscaping are in an intercourse, although big money and made efforts could to some extent provide marginal mitigation or a compromised solution to the afore-cited problems. Additionally, in many cases other aspects than energy production are given secondary significance, consequently causing them to suffer the one-sided terms dictated solely by the energy production aspects.